The present invention relates to an expansion device for increasing the volume or capacity of a bulk material container. In particular, the invention relates to an expansion device for the grain tank of a combine harvester.
Document EP 1 564 157 A2 describes an expansion device wherein a plurality of wall panels is connected in an articulated manner to a frame formed by the grain tank of the combine harvester itself, and which can be pivoted from a position in which the wall panels rest flat against the frame and close the grain tank into a position in which the wall panels extend above the frame. Triangular connecting panels fill the gaps between the wall panels, which extend away from each other in the upward direction when in the pivoted-out position such that a container is formed, which is closed around the circumference thereof.
The volume or capacity of this conventional expansion device, however, is limited by the need to select the width of the wall panels transversely to the pivot axis thereof to be so small that two opposing wall panels in the closed position can be folded over the opening of the frame without overlapping one another. If the width were greater, then an attempt to fold the wall panels over the frame opening would be blocked by the wall panels and connecting panels impacting one another.
An expansion device for a bulk goods container is described in DE 10 2007 003 653 A1, in which the volume or capacity is increased by the use of wall panels. Each of the wall panels is formed by two segments connected to one another in a pivotable manner. An inner segment of the wall panels, which connects an outer segment to the frame in each case, assumes a substantially horizontal orientation when in the pivoted-out position. As a result, although the dimensions of the expansion device can be markedly increased in the horizontal direction, this produces regions from which bulk material can no longer easily flow toward the frame when the device is emptied. Therefore, in order to empty the expansion device completely, auxiliary means such as a fluidization device are required or movements of the segments must be directed into a position in which the bulk material flows out completely.